1. Field of the Invention
The present invention generally relates to analog data acquisition device for effecting an analog-to-digital conversion and a programmable voltage comparison. More particularly, the present invention relates to an analog data acquisition device which has a function to effect analog-to-digital conversion by a successive approximation system and another function to compare a voltage designated by a program with an input analog voltage to detect which one is larger (or smaller) in amplitude therebetween, these functions being easily changed over therebetween.
2. Description of the Prior Art
An approach in which a digital computer is used to effect analog-to-digital conversion by a successive approximation system and to compare an input analog signal with a reference value to detect which one is larger (or smaller) therebetween is disclosed in "ANALOG-TO-DIGITAL CONVERTER" by C. A. Walton, G. H. Royer and C. H. Proster, Jr., IBM Technical Disclosure Bulletin, Vol. 7, No. 10, March 1965. The approach executes analog-to-digital conversion by successively executing a successive approximation system program stored in a core storage and executes a program for a mere comparing operation to make comparison of an analog data with a reference voltage to detect which one is larger therebetween.
A digital computer may make various types of operations by changing programs stored in the core storage. Since the operation of the analog-to-digital converting operation per se is program control, however, the converting operation is slow. Further, when the digital computer per se executes the analog-to-digital conversion, it can not execute other processings. This deteriorates the cost/performance of the digital computer.
A high speed analog-to-digital converter using a successive approximation register for the successive approximation system analog-to-digital conversion is also known well. So far as we know, however, there is not an approach in which a voltage specified by a program is compared with an input analog voltage to detect which one is larger (or smaller) in amplitude therebetween and an analog-to-digital conversion is also performed, these two operation modes being switched or selected in an easy way.